I figured it out how you +Fe types make your characters.
You observe -Fi -- bad feelings -- and seeing it resolve to set yours and others' minds minds toward positive thoughts. To do this, one must differentiate the psyche, suppressing the "bad" impulses into the subconscious and raising up the "good" impulses to consciousness. Your constant observation of this process in other and in yourself is the meant by which you create the complex characters +Fe imagines. It is also the means by which you inspire others to reach toward the higher virtues in life.